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Hostile Intent: Alternative Combat Rules for Mongoose Traveller

This article was the featured article in the October 2012 issue of Freelance Traveller.


In many ways, Mongoose improved on the Classic Traveller game engine’s combat rules. In others, I feel they’ve added some unnecessary complexity.

In particular, the initaitve/recoil/heft system is a bit fiddly. I also don’t care for the way things can be “gamed” such as autofire or how a player chooses which characteristics get damaged after Endurance.

Overall, the object of these rules is to make combat play faster with less book-keeping. I’ve also tried to add some areas that actually needed some detail, such as vehicle maneuvering.


The initiative roll is 1d6 instead of 2d6. Certain careers get a DM if the character completed a term successfully:

Leadership and tactics rolls use the ‘aid another’ DMs, which means that rolling poorly will result in an initiative penalty. Surprised characters have their initiative roll halved.

Regardless of DMs, the maximum initiative possible is 12, and the minimum is 1.

The Combat Round

Characters act in order of their initiative numbers, highest to lowest. If multiple characters have the same initiative number, they take simultaneous actions. The method used to declare simultaneous actions is up to the referee.

A character can choose to delay their action until a lower number, and if the count drops to 1 the character starts the round delaying at 12. This may mean that in some cases a character who delays may end up acting twice in a given round. This is balanced by the lack of action in the previous round.

Defensive Actions

These rules replace the rules for reactions. A defensive action is a significant action, and there are two basic defenses:

Dodging: This is used to avoid ranged attacks. The character applies their Athletics (co-ordination) and Dexterity DM (if positive) as negative DMs to all ranged attacks made against them. The minimum Dodge DM is -1.

Parrying: This is used to defend against melee attacks. The character applies the appropriate Melee specialty and positive Dexterity DM as negative DMs to melee attacks made against them, with a minimum of -1.


Aiming has no effect on melee attacks, and a profound effect on ranged attacks. A ranged attack conducted without first taking an Aim action in the same round is called snap fire.

Melee Combat

All melee combat is at personal to close range. Most melee weapons can only strike within personal range, while reach weapons (the pike and halberd) may strike at close range with a -3 DM. Some large animals may have Reach weapons as natural weapons.

Relative stance applies a DM as follows:


Attacker Defender Attack DM
Standing Crouching +1
Prone +2
Crouching Standing -1
Prone -1
Prone Standing -2
Crouching -1

As in the core rules, the melee task uses the character’s Strength DM and the appropriate Melee specialty.

Ranged Combat

Instead of a table, all ranged weapons have an effective range band that uses the weapon’s base ranged attack DM. Each successive range band increases the difficulty as follows:


Range Band Aimed Snap
Base Range 0 -3
1 band beyond Base -3 -6
2 bands beyond Base -6 No

When converting weapons from the core rulebook, use the following guidelines:

For example, an assault rifle converts to a base range of medium. The difficulty profile would be:


Range Band Aimed Snap
To Medium 0 -3
Long -3 -6
Very Long -6 No

Recoil and Heft

These numbers are largely ignored except:

Disoriented characters can take no actions until they succeed at a Zero G task (average; Dex; minor action) to right themselves.

Ammo and Rate of Fire

Most of the time, even trained soldiers will use the highest rate of fire possible when in combat. To reflect this, all weapons except autofire weapons have only one rate of fire. With weapons other than single-shot weapons, the magazine value is number of attacks instead of the individual number of bullets or charges.

Rapid Fire: Most non-autofire weapons with a magazine of 10 or more are rapid fire. Halve their magazine value, to reflect the faster rate of fire. Round fractions down. Rapid fire weapons get a +1 DM to attacks.

Autofire: Divide the magazine by the autofire number, rounding down. Autofire weapons can be used on one of two ways: They can fire at a single target, getting the autofire number as a positive DM to hit, or the character can fire at a number of targets equal to the autofire number, using up a “shot” for each target and suffering a -3 DM vs. all targets. Each target is a separate attack roll.

Shotguns: All shotguns have a +2 DM to hit since they fire a spray of pellets rather than a single projectile.

Armor and Weapon Effects

If you have the Central Supply Catalog, use the armor rules from there. If you have only the Core Rulebook and/or Mercenary:

If you have CSC, apply the armor rules as listed, except for melee weapons. Weapons listed as “Mace” should be Semi-AP weapons. “Armor reduced” weapons are Armor Piercing, and “Armor halved” weapons are Super-AP.


The effects of explosives are streamlined. If you have the CSC, use the primary radius as the basis. An explosive has two possible areas of effect:

Blast: The attack does full damage to the target, and half damage to targets in the primary radius.

Frag: The attack does full damage to the target and to all targets in the primary radius, and half damage to targets out to twice the primary radius.

Armor-piercing effects are only applied to the primary target. Soft-target and area effects are applied to the primary target and targets in the blast/frag radius.

Only a single damage roll is made, as opposed to damage rolls for each target at differing distances. Placed charges add the Effect of the Explosives skill roll to damage.

Explosive Special Effects: The special effects for explosives from the Core Rulebook are as follows:


Explosive Damage Effects
Grenade, Frag 5d6 Frag 3m, Soft Target
Grenade, Stun 3d6 Area Eff., Frag 1.5m, Stun
Plastic Explosive 3d6 Frag 6m
Pocket Nuke 2d610 Frag 45m
Rocket, TL6 4d6 AP 8, Blast 3m
Rocket, TL7 4d6+3 AP 8, Blast 3m
Rocket, TL8 5d6 AP 10, Blast 3m
Rocket, TL9 5d6+5 AP 10, Blast 3m
TDX 4d6 Frag 12m

Damage and Injury

All attack rolls should have a timing die rolled with them like any other task roll. In this case, the timing determines hit location rather than how long the task takes. Hit location determines the order in which characteristics suffer damage, referred to here as wounds:


‘Timing’ Location Wounds
1,2 Arm/Leg STR, END, DEX
3,4,5 Torso END, STR, DEX
6 Head DEX, END, STR

Damage from explosions and area-effect weapons (or falling) ignores the hit location rule, and should be applied as torso hits.

Roll damage as normal. A character with at least two characteristics above zero but less than full is considered injured.

Incapacitation: When two characteristics are reduced to zero, the character is incapacitated and knocked unconscious. When a character is first incapacitated, they must make a task roll for each characteristic at zero (using the DM for the characteristic’s full normal value). If the roll fails, the characteristic is reduced by an amount equal to effect.

Incapacitated characters that regain consciousness can only take free actions. A conscious incapacitated character that suffers further damage doesn’t need to make any more “saving throws” for characteristic loss, but will be knocked unconscious again.

Death: When all three characteristics are reduced to zero the character is mortally wounded but not necessarily dead. The character makes a “not quite dead” yet roll that’s similar to the “saving throw” for incapacitation mentioned above. Apply any damage in excess of what reduced the 3rd characteristic to zero as a negative DM to this roll. If the character succeeds, they instead survive with 1 point on that last characteristic rather than being dead.

Stun Damage: Stun damage is rolled normally, and weapons that have split damages should use the full stun damage value + the non-stun value. For example the shock baton in CSC does 2d6 + 1d6 stun. This would convert to 2d6 stun. Half-dice convert to a +3 to damage.

Compare stun damage to the character’s Endurance. If the damage is equal to or greater than this, the character is knocked out for 1 minute. If the damage is twice Endurance, the character is knocked out for 10 minutes, and each extra multiple of Endurance adds another 10 minutes. First aid won’t revive the character during this time.

Blunt conventional weapons can be used to deal stun damage, but have a -1 DM to hit and have their damage rolls halved when using them this way.

Healing and Medical Treatment

Injured characters heal 3 + End DM points per day they rest, and End DM points per day they remain active. Incapacitated characters heal End DM points per day only.

Healing is always applied in the order of Dex, Str, then End unless otherwise noted.

First Aid: First aid can be used to either heal injured characters, or revive an unconscious character. If used to heal, the patient heals effect points. First aid is a Medic (Edu) task with a time increment of 1 minute.

Surgery: Surgery can benefit patients if they are treated within 1 hour of incapacitation. Surgery can heal damage equal to the effect of the successful roll. This healing can be used to heal wounds, or can be traded on a 2:1 basis to remove permanent injury suffered to characteristics. However, failed surgery causes effect damage. Surgery is a Medic (Dex) task with a time increment of 10 minutes.

Medical Care: Long term medical care doesn’t require a task roll (although timing should be rolled if it matters, with an increment of 1 hour). A character can heal a patient’s injuries at a rate of 2 + Medic skill, and these points can be distributed as desired. A doctor can perform this task several times a day as time allows.

Self-Doctoring: A non-incapacitated character can self-medicate, but this becomes Difficult rather than Average. Regaining of characteristics is at half the rate for Medical Care.

Healing Limits: A character can only receive the benefits of medical care once per day, and only the first successful attempt is used.

Injury and Recovery Example

Brooke (UPP 596A87) takes a shotgun blast to the torso, suffering 14 points of damage. This reduces her End and Str to zero, and takes two points off her dex (070), and incapacitates her. She has to roll saves for her Str and End, and rolls 6 and 8 respectively. This drops her maximum Strength to 3.

Her brother Sam is a skilled surgeon (UPP 694878, Medic 2), and sets to work on her soon after the rest of the Tranquility crew finishes with the pirates. Sam does really well on his surgery roll, roll a total of 14 for an effect of 6. Sam decides to use 4 points to heal the 2 points of permanent Strength damage, and the other 2 points towards healing wounds. This brings Brooke’s physical UPP to 090.

Sam continues to provide medical care, and adds 4 points to Brooke’s natural healing of -3 per day. This means she gains 1 point of Strength and is no longer incapacitated. On day 2, her natural healing rate is now 1 point with rest, plus Sam’s medical care of 4 points. This brings her Strength up to full and her End to 1.

Brooke decides she’s been in bed long enough, and begins to do small things around the ship (much to her brother’s consternation). She does consent to continued medical care, so she continues to heal slowly, gaining 2 points on the 3rd day, and 3 points to fully heal by the 4th day.

Vehicles: Maneuvering

One big hole in the Traveller rules has always been vehicle maneuvering. The Core Rulebook is no different. For this, apply the following simple rules:

Vehicle Damage

Vehicle damage is greatly simplified, and uses the hit location system developed for characters.

The first step is to divide any damage done to the vehicle by 3, rounding down, do determine the number of “hits.” As with character damage, apply the timing rule using a modified version of the vehicle damage table:


Timing Die Vehicle External Vehicle Internal Drone/Robot
1 Hull Structure Hull
2 Hull Structure Hull
3 Hull Passengers Hull
4 Weapon Cargo Weapon/Limb
5 Drive Power Plant Drive
6 Sensors Computer/Cockpit Sensors/Computer

Calculate the full hits value vs. the given location. On a vehicle, use the listed external system first. If the hull is depleted go to the same row on internal hits.

If the vehicle is without a weapon, drive, or sensors, treat as a hull hit.

If a given location use two systems, apply hits to the first, then the second, then to hull or structure as appropriate.

Hits to cargo transfer to the cargo (sub-vehicles or items). Passenger or crew hits convert to 1 die per hit, divided evenly as possible in full dice among the various crew, and treated as area effect damage.

Vehicle Damage Example

The PCs are traveling in an ATV in rugged terrain, and are ambushed by bandits who start the festivities by firing the two TL 8 rocket launchers they have at the ATV.

The first attack roll is an 8, and the AP value of 10 for the rocket launcher negates all but two points of the ATV’s armor. This leaves 2 points to resist the damage roll 15, for 13 damage. This translates to 4 hits, and the timing roll of 3 is a hull hit, dropping the ATV’s hull to 1 point.

The second rocket attack is a 10, which adds two to the damage roll of 15, which is a net 15 with the armor. Timing this time is 6, for 5 hits of damage. The first two take out the vehicle’s comms and sensors, and the 3rd hit reduces the hull to zero. The remaining damage goes to the internal column. As the ATV has no on-board computer, the remaining 2 hits are applied to the cockpit. As there is only one crew person, the character driving, that person suffers 2d6 damage.

Sample Weapon Data

The table below shows the altered combat statistics for selected weapons from the Core Rulebook.

Weapon Range Damage Magazine Notes
Autopistol Short 3d6-3 7 Rapid Fire
Club Melee 1d6   Blunt
Dagger Melee/Close 1d6+2    
Gauss Rifle Long 4d6 20 Autofire 2
Laser Carbine Medium 4d6 25 No Recoil; Rapid Fire
Rapier Melee 1d6+4   Parry 2
Rifle Long 3d6   Armor Piercing 1
Rocket Launcher (TL6) Long 4d6 1 Armor Piercing 8; Blast 3m
Shotgun Short 4d6   High Recoil; Shotgun; Soft Targets
Staff Melee 2d6   Blunt; Reach
Stunner Short* 2d6 50 Area Effect; No Recoil; Rapid Fire; Stun
Stunstick Melee 1d6   Stun
* The maximum range for a stunner is also Short.